Vertebral scale system to measure heart size in growing puppies.

OBJECTIVE

To determine relative heart size in clinically normal puppies and assess whether relative heart size changes with growth.

DESIGN

Prospective radiographic study.

ANIMALS

11 puppies without evidence of disease.

PROCEDURE

Standardized measurements of the long and short axes of the heart, midthoracic vertebrae, and other structures were made at 3, 6, 12, and 36 months of age. Measurements were recorded in millimeters and number of thoracic vertebral lengths spanned by each dimension, measured caudally from T4 on lateral radiographic views. The long and short axis measurements of the heart, expressed in vertebral lengths, were added to yield vertebral heart size.

RESULTS

Mean +/- SD vertebral heart sizes on lateral radiographic views at 3, 6, 12, and 36 months of age were 10.0 +/- 0.5, 9.8 +/- 0.4, 9.9 +/- 0.6, and 10.3 +/- 0.6 vertebrae, respectively. Significant differences were not detected.

CONCLUSIONS AND CLINICAL RELEVANCE

Vertebral heart size measurements in puppies are within the reference range for adult dogs (9.7 +/- 0.5 vertebrae) and do not change significantly with growth to 3 years of age. Standards for determining cardiac enlargement are similar in puppies and adult dogs.